build(deps-dev): bump sphinx from 3.0.0 to 3.0.3

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.0.0 to 3.0.3.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/3.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v3.0.0...v3.0.3)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements/dev.txt

@@ -48,7 +48,7 @@ secretstorage==3.1.2      # via keyring
 six==1.14.0               # via bleach, cryptography, packaging, paver, python-dateutil, readme-renderer
 snowballstemmer==2.0.0    # via sphinx
 sphinx-issues==1.2.0      # via -r requirements/dev.txt
-sphinx==3.0.0             # via -r requirements/dev.txt, sphinx-issues, sphinx-rtd-theme
+sphinx==3.0.3             # via -r requirements/dev.txt, sphinx-issues, sphinx-rtd-theme
 sphinx_rtd_theme==0.4.3   # via -r requirements/dev.txt
 sphinxcontrib-applehelp==1.0.2  # via sphinx
 sphinxcontrib-devhelp==1.0.2  # via sphinx